What are the potential issues with using IP addresses to detect multi-accounts in PHP scripts?

Using IP addresses to detect multi-accounts in PHP scripts can be unreliable due to shared networks, VPNs, and dynamic IP addresses. To improve accuracy, consider implementing additional verification methods such as email verification or phone verification. 

// Example code snippet for implementing email verification along with IP address check

// Check if the email is already registered
$email = $_POST['email'];
$query = "SELECT * FROM users WHERE email = '$email'";
$result = mysqli_query($connection, $query);

if(mysqli_num_rows($result) > 0){
    // Email already exists, check if the IP address is the same
    $user = mysqli_fetch_assoc($result);
    if($user['ip_address'] == $_SERVER['REMOTE_ADDR']){
        // Allow registration
    } else {
        // Display error message for potential multi-account
    }
} else {
    // Proceed with registration
}

Keywords

IP addresses multi-accounts detection PHP scripts security vulnerabilities

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